Provided by: postfix_3.1.0-3_amd64 bug

NAME

       flush - Postfix fast flush server

SYNOPSIS

       flush [generic Postfix daemon options]

DESCRIPTION

       The  flush(8) server maintains a record of deferred mail by destination.  This information
       is used to improve the performance of the SMTP  ETRN  request,  and  of  its  command-line
       equivalent,  "sendmail  -qR"  or  "postqueue -f".  This program expects to be run from the
       master(8) process manager.

       The record is implemented as a per-destination logfile with as contents the queue  IDs  of
       deferred  mail.  A logfile is append-only, and is truncated when delivery is requested for
       the corresponding destination. A destination is the part on the  right-hand  side  of  the
       right-most @ in an email address.

       Per-destination  logfiles  of deferred mail are maintained only for eligible destinations.
       The list of eligible destinations is specified with the  fast_flush_domains  configuration
       parameter, which defaults to $relay_domains.

       This server implements the following requests:

       add sitename queueid
              Inform  the  flush(8) server that the message with the specified queue ID is queued
              for the specified destination.

       send_site sitename
              Request delivery of mail that is queued for the specified destination.

       send_file queueid
              Request delivery of the specified deferred message.

       refresh
              Refresh   non-empty   per-destination   logfiles   that   were    not    read    in
              $fast_flush_refresh_time  hours,  by  simulating  send requests (see above) for the
              corresponding destinations.

              Delete   empty   per-destination   logfiles    that    were    not    updated    in
              $fast_flush_purge_time days.

              This request completes in the background.

       purge  Do a refresh for all per-destination logfiles.

SECURITY

       The  flush(8)  server  is  not security-sensitive. It does not talk to the network, and it
       does not talk to local users.  The fast  flush  server  can  run  chrooted  at  fixed  low
       privilege.

DIAGNOSTICS

       Problems and transactions are logged to syslogd(8).

BUGS

       Fast  flush  logfiles are truncated only after a "send" request, not when mail is actually
       delivered, and therefore can accumulate outdated or redundant data. In order  to  maintain
       sanity,  "refresh"  must  be  executed periodically. This can be automated with a suitable
       wakeup timer setting in the master.cf configuration file.

       Upon receipt of a request to deliver mail for an eligible destination, the flush(8) server
       requests  delivery  of  all  messages  that  are  listed  in  that  destination's logfile,
       regardless of the recipients of those messages. This is not an issue for mail that is sent
       to  a  relay_domains  destination  because  such mail typically only has recipients in one
       domain.

CONFIGURATION PARAMETERS

       Changes to main.cf are picked up automatically  as  flush(8)  processes  run  for  only  a
       limited amount of time. Use the command "postfix reload" to speed up a change.

       The  text  below  provides  only  a  parameter  summary.  See postconf(5) for more details
       including examples.

       config_directory (see 'postconf -d' output)
              The default location of the Postfix main.cf and master.cf configuration files.

       daemon_timeout (18000s)
              How much time a Postfix daemon process may take to handle a request  before  it  is
              terminated by a built-in watchdog timer.

       fast_flush_domains ($relay_domains)
              Optional  list  of destinations that are eligible for per-destination logfiles with
              mail that is queued to those destinations.

       fast_flush_refresh_time (12h)
              The time after which a non-empty but unread per-destination  "fast  flush"  logfile
              needs to be refreshed.

       fast_flush_purge_time (7d)
              The time after which an empty per-destination "fast flush" logfile is deleted.

       ipc_timeout (3600s)
              The  time limit for sending or receiving information over an internal communication
              channel.

       max_idle (100s)
              The maximum amount of time that  an  idle  Postfix  daemon  process  waits  for  an
              incoming connection before terminating voluntarily.

       max_use (100)
              The  maximal  number  of  incoming  connections  that a Postfix daemon process will
              service before terminating voluntarily.

       parent_domain_matches_subdomains (see 'postconf -d' output)
              A list of Postfix features where the pattern "example.com" also matches  subdomains
              of example.com, instead of requiring an explicit ".example.com" pattern.

       process_id (read-only)
              The process ID of a Postfix command or daemon process.

       process_name (read-only)
              The process name of a Postfix command or daemon process.

       queue_directory (see 'postconf -d' output)
              The location of the Postfix top-level queue directory.

       syslog_facility (mail)
              The syslog facility of Postfix logging.

       syslog_name (see 'postconf -d' output)
              The  mail  system  name that is prepended to the process name in syslog records, so
              that "smtpd" becomes, for example, "postfix/smtpd".

FILES

       /var/spool/postfix/flush, "fast flush" logfiles.

SEE ALSO

       smtpd(8), SMTP server
       qmgr(8), queue manager
       postconf(5), configuration parameters
       master(5), generic daemon options
       master(8), process manager
       syslogd(8), system logging

README FILES

       Use "postconf readme_directory" or "postconf html_directory" to locate this information.
       ETRN_README, Postfix ETRN howto

LICENSE

       The Secure Mailer license must be distributed with this software.

HISTORY

       This service was introduced with Postfix version 1.0.

AUTHOR(S)

       Wietse Venema
       IBM T.J. Watson Research
       P.O. Box 704
       Yorktown Heights, NY 10598, USA

       Wietse Venema
       Google, Inc.
       111 8th Avenue
       New York, NY 10011, USA

                                                                                  FLUSH(8postfix)